How Air Pollution Kills

The biology of death caused by particulate matter.

This is a transcript of the video.

Brian Palmer, writer, NRDC: A coal-induced smog killed 4,000 Londoners in just four days in 1952. Researchers spent the next six decades figuring out what makes air pollution so deadly.

I'm going to explain what they found, using this and this. Now, we're going to focus on just one kind of air pollution: particulate matter, which is just tiny bits of airborne stuff, like the leftovers from burning coal and gasoline.

How tiny is it? Well, if this a cross-section of a human hair, particulate matter is between this big and that big. The smaller the particle, the more hazardous to your health. To see why, let's take a field trip—up my nose.

The nose is a chaotic place. Air is blowing in all directions, there are little hairs, and mucous is everywhere.

The larger particles tend to get caught up and blown out. The smaller particles are more likely to make it past the nose, down the windpipe, and into your lungs.

Now these little guys are immune cells. They patrol the lungs looking for intruders, like this bacteria. When they find one, they gobble it up, digest it, and get it out of the body. But the immune cell can't digest particulate matter. So it calls in reinforcements; other immune cells flood the lungs.

Now this is bad because immune cells are programmed killers. A whole bunch of them hanging around inflames the delicate tissue of the lungs. This inflammation can cause or worsen asthma, emphysema, and other respiratory diseases.

But the air pollution story doesn't end in the lungs.

The smallest particles are so tiny that the lungs' immune cells don't even bother with them. These particles settle onto the alveoli, which are tiny air sacs that pass oxygen—and this particle—into your blood.

Now the particle floats along in your bloodstream until it encounters an obstacle, like the plaque that builds up on the walls of our arteries.

Now, your blood is supposed to be sterile and pristine, so the immune cells in here will attack even the tiniest particles, and you get inflammation. The arteries already narrowed by plaque become nearly impassible, blood flow slows to a trickle, and you have a heart attack.

But that's just one way air pollution can kill you. There are many kinds of air pollutants, and many more ways they can kill through both short-term and long-term exposure.

Outdoor air pollution kills four million people every year. That's why public health authorities are fighting for tougher air pollution rules. It's also why loosening emissions limits on power plants, cars, and other sources is a very bad idea.

Because air pollution kills.

In Conversation

David Doniger, senior strategic director of the Climate & Clean Energy Program, has helped shape federal and global climate-related policies since he joined NRDC in 1978.

onEarth Story

Plus, get ready for the rise of hermaphroditic frogs, and the EPA’s Science Advisory Board can’t meet until after the agency corrupts science.

onEarth Story

Plus, NOAA deletes important renewable energy research, and the border fence steamrolls a national monument.

onEarth Story

The administration relocates science jobs, refuses to fill others, and tosses a lifeline to polluters (while silencing citizens).

Policy Primer

In New York, a tax on driving downtown would also generate sorely needed funding for the transit system that most residents rely on for their daily commutes.

Action Figure

Anaïs Peterson is busy organizing, educating, and ushering in a new era of environmentalism in the Steel City.

Midwest Dispatch

A county in eastern Iowa has been replacing gravel with slag, a steel industry byproduct. It’s hard, sharp, and potentially a public health concern.

Northeast Dispatch

The tireless efforts of locals are reshaping one of New Jersey’s most polluted areas.

onEarth Story

Interior’s Bernhardt helped bury a damning pesticide report, the Clean Air Committee goes soft on soot, and Trump nominates a climate change denier to the Fed board.

Western Dispatch

Local environmental justice groups get a boost from the city’s Clean Up Green Up policy, which brings green zoning to three heavily polluted communities.

Midwest Dispatch

The air in southwestern Indiana is bad enough without the emissions from yet another proposed polluter.

Western Dispatch

The largest ferry system in the United States prepares to stop using diesel fuel to help Washington achieve its climate action goals.

What's At Stake

Climate change poses challenges to our well-being—and the more carbon pollution we put into the air, the worse things will get.

Midwest Dispatch

So take it somewhere else, says Chicago’s Southeast Side.


How smog, soot, greenhouse gases, and other top air pollutants are affecting the planet—and your health.

Personal Action

As rising carbon emissions boost smog and pollen production, even breathing can be a challenge. Here’s what you can do to help clear the air.

What's At Stake

The administration’s assault on our environment and health is unlike any threat we’ve ever faced.

NRDC in Action

NRDC’s Gina Ramirez is helping to bring attention to the wafts of manganese dust that plague her family and neighbors on Chicago’s Southeast Side.

Senor Codo
onEarth Story

New research suggests the dirty air that pregnant women breathe might increase the risk of autism spectrum disorder in their children.


Every time you go outside, you may be inhaling harmful chemicals. But don't hold your breath. Just use your head.

On Location

Southeast Side residents have been plagued by a heavy metal that’s known to negatively impact the brain function of children.

Join Us

When you sign up you'll become a member of NRDC's Activist Network. We will keep you informed with the latest alerts and progress reports.